This invention relates generally to a device for controlling the temperature of fluid in a closed-circuit system. More specifically, the invention relates to an integrated heat exchange and fluid control device for an engine, such as an automobile engine.
Automobile engines optimally operate in a known temperature range. Typically, an automobile's engine temperature is below this optimal range during engine warm-up. It is therefore desirable to cause the engine to reach its optimal temperature range as quickly as possible by not cooling the engine fluid immediately after warm-up. However, engines will eventually reach temperatures above this optimal range if left uncooled, so it is thereafter desirable to cool the engine fluid so the engine does not exceed the maximum optimal operating temperature, and is controlled within the optimal temperature range.
Additionally, engine fluid temperature control systems are typically closed-circuit systems with a constant fluid volume. Therefore, it is desirable for a fluid temperature control device to be able to quickly and accurately adjust the amount of fluid that is cooled without adjusting the overall fluid volume in the system.
Fluid temperature control devices typically control the operating temperature of engine fluid by using a bypass loop, such as a bypass circuit, that directs fluid away from the heat exchanger. Presently, bypass circuits are located, externally from the heat exchanger, either internally or externally to the engine, in order to minimize heat transfer of the fluid in the bypass circuit. However, an external fluid bypass circuit requires added components such as additional seals, housing structures, and tubing. External bypass circuits also cause unnecessary complexities during system diagnosis and repair because the system components are dispersed throughout the internal structure of the engine. Additionally, traditional bypass circuits can reduce the efficiency of cooling system fluid fill and fluid evacuation during manufacturing and during repair.